Manufacture of electric lamps and the like



May 25 926; 1,585,803

C. C. VAN VOORHIS MANUFACTURE OF ELECTRIC LAMPS AND THE LIKE Filed June 21, 1922 TO Vfl C UUM PUMP HND 5 OUR CE OF INER T Q56 To me UUM PlZMPfl/VD $001905 OF/NEET /75 INVENTORI CLE Tus 0. van! vooaw/s 'ATTORNEY Patented May 25', 1926.

- UNITED I STATES 1,585,803 PATENT OFFICE.

CLETUS CLINTON VAN YOQBHIS, OF EAST ORANGE, NEW JERSEY, ASSIGNOB TO WEST- INGHOUSE LAMP COMPANY, A CORPORATION OF PENNSYPN'ANIA.

MANUFACTURE OF ELECTRIC LAMPS AND THE LIKE.

Application filed June 21, 1922. Serial No. 568,861.

This invention relates to the manufacture of electrical devices comprising evacuated or gas-filled envelopes and more particularly to the introduction of unstable 6 volatile. substances into electric lamps and the like.

Anobject of my invention is the provision of a method of handling unstable substances whereby they-may be used ina substantially 10 pure condition, uncombined with oxygen, water vapor and the like.

Another object of m introduction of chemically or getters into envelopes'of electric lam s, radio-tubes, photo-electric cells and the like in minute quantities and in substantially pure" condition? A further object of my invention is the provision of a method for supplying a small quantity of a pure metal, such as one of the alkali metals, uncombined with oxygen, water vapor or other substance having an ailinity therefor, to an electric glow lamp or the like. 1

Other objects and advantages of the in vention will be apparent as the description proceeds.

vIn the manufacture of "electric devices, such as rare-gas glow lamps, vacuum or gas-filled incandescent lamps, vapor lamps,

photo-electric cells and the like, it is desirable, in many cases, to introduce a small quantity of an active substance in the pure state, such as a volatile metal. In glow J lamps, for example, it is desirable to introduce an alkali metal to lower the starting and operating voltage "thereof. On account of the rapid action of oxygen and moisture on many of such substances, they must be kept from contact with the air to prevent the combination with oxygen, moisture and other substances having an aflinity therefor. Some substances, suchas potassium and phosphorus, will, in some cases, ignite spontaneously when exposed to the action of water and air, respectively. Consequently, active substances of the aforementioned character cannot be introduced into electric lamps and the like and remain in a pure uncombined condition unless the air has previously been evacuated therefrom. 1

-The method commonly used is to construct the bulb or the like into which the invention is the volatile metal or'getter is to be introduced with a side tube. con aining some of such active substances 'metal, such as pyrex or lime substance. The metal or volatilized into the bulb a ter which the side tube is sealed oif of the bulb. According to the previously described method, the side tube is not especiall adapted for protecting the substance to introduced from the action of the atmosphere and is used for supplying only one bulb with a volatile metal or the like, and the process is, therefore, expensive and slow.

etter' is then In accordance with my invention, I may use the following method for introducing volatile substances into electric lam and the like. Although I will descri e my method with reference to the introduction 'of volatile metals, it is to be understood that other volatile substances, such as phosphorus, for instance, may be introduced'in the same manner, if desired.

A purified volatile metal is 'first put into specially constructed glass tubes by. any known method, that is, the metal 'may be melted in vacuo or in an inert atmosphere and pouredinto a tube constructed of a glass which is not attacked by the melted glass. The tubes are so constructed that, even when open at one end, the volatile metal therein .is rotected substantially from atmospheric 'actlon. One of these tubes containing metal may be connected to a system for exhausting or gas-charging a lamp or a series of lamps. The lamp may be exhausted and some of the metal in the tube be then melted and vaporized until the desired amount is introduced into the exhaust system where, it may be flushed into the lamp by a flow of inert gas or allowed toflow into the-lamp by its own pressure. Y

My invention. will better be understood .by reference to the accompanying drawing in which,

Fig. 1 is a side elevation of a tube for holding a volatile metal or other substance; Fig. 2 is a side elevation illustrating a rare-gas glow lamp and one ofsuchtubes connected to a system for exhaustion and.

gas charging' Fig. 3 is a side elevation showing a modification of the arrangement shown in Fig.

2; and, Fig. 4 is a shownin Fig. 3. Y Q Q In practic1ng my invention, the tube or cont iner l/(F g- 1), o p i ing an en.-

plan view of the arrangement ion larged portion or reservoir 2, a central contracted portion 3, and an end portion 4, may be filled with a volatile metal or other substance '5 which preferably completely fills the reservoir 2 and extends part Way through the contracted portion 3. The end portion 4 may be sealed by tipping off at 6 so that the volatile metal 5 may be kept for any length of time until it is desired to use the same. The middle section 3 of the tube is narrow, the inside diameter beingpreferably about inch, though it may be larger or smaller. The length of this narrow section may vary from approximately inch to an indefinite length, being preferably about 2 inches.

The enlarged portion 2 preferably has a diameter larger than that of the middle section 3, so as to hold the required amount of metal without being unduly long. The end portion 4. may have av diameter equal to or greater than the middle portion 3. The tube may be bent at the narrow part 3, so that it may be sealed to an exhaust system, with the end portion 4 substantially horizontal and the reservoir 2 extending to a higher elevation than the narrow part 3 so that, when the metal is melted, it will fi-ow by gravity into the narrow part 3 and thus expose only a small surface to be-acted on by air or moisture. The tube 1 ispreferably constructed of transparent material, such as pyrex or lime glass, which is not appreciably attacked by melted alkali metalsor the like.

In order to use the metal 5 in the tube 1, part of the end portion 4 is cut off, and the tube 1 is sealed to a pipe or tube 7 of an exhaust system, (Fig. 2) at a point 8 preferably near to the lamp 9 which is to be exhausted. The exhaust system may comprise a connection to a vacuum pump or the like (not shown) and a source of inert gas, not shown) if it is desired to produce gas-filled lamps. The lamp 9 may be exhausted through contraction 11, and a suitable amount of said metal distilled from the tube 1 by means of heat applied in any desired manner. While the portion of the tube from the metal in the reservoir to the connection to the exhaust pipe is kept hot, the exhaust pipe 7 may be warmed up in the region from the contraction 11 to some distance'beyond the connection 8 between the tube 1 and the exhaust pipe.- A current of a gas, such as argon, inert to the, volatile metal, may then .be allowed to slowly stream through the contraction. 11, thus sweeping the desired amount of volatile metal vapor into the lamp 9.

Some of the volatile metal may be distilled directly from the tube 1 into lamp 9, through the exhaust pipe 7, without using any inert gas to sweep orflush the metal vapor in, but the inert gas streaming through the tube 7 makes it posible to introduce the desired amount of volatile metal into the lamp in a much easier and quicker manner than without its use. The metal will condense and deposit on the inside of the lamp 9, and the gas may then be pumped back into a reservoir by means of any suitable pump.

In case an inert filling is to be put into the lamp 9, as in the manufacture of raregas glow lamps, the volatile metal may be introduced at the time the filling is made, thus obviating the necessity of pumping out the gas used to sweep in the volatile metal vapor. This procedure has the added advantage, in the case of some metal vapors, such as those of the alkali metals, in that such metals have a purifying action on gases which are inert to them.

.If a considerable quantity of the volatile metal is to be introduced, the tube 1 may be inclined so that the metal may be melted and caused to flow down through exhaust tube 7 and into lamp 9.

After the lamp 9 has been suitably treated and tipped off at the contraction 11 and while a new lamp is being connected to exhaust tube 7, air will come into contact with the metal in tube 1. However, as section 3 of tube 1 is narrow and normally closed by a column of metal, the amount of metal surface exposed and oxidized will be very small, because of the slow diffusion through such a narrow tube of a fresh supply of oxygen or moisture to this surface and because the thin film of oxide first formed serves as a protective coating against further action.

Such oxide, in some cases, will not be volatile enough to distill out of tube 1, when metal vapor is distilled therethrough. In other cases, it may easily be driven far up into exhaust tube 7 with a very small amount of metal where it will not interfere any further with the process, this being best accomplished as the exhaustion of the bulb is nearing completion. By the fmethod just described, the volatile metal or other active substance may be introduced into a large number of lamps, bulbs or the like, from one tube or container, without requiring the sealing of a container to each bulb and subsequent sealing-ofl of the same.

Figs. 3 and 4 show a modified arrangement of apparatus suitable for introducing a volatile metal to a number of lamps at once, instead of into only one lamp at a time, as previously described. The apparatus for practicing this method for a plurality of lamps or other vessels may comprise a lass manifold 12 composed of a multiplicity of tubes 13 going out of a common central chamber 14. From this chamber 14, which is kept as small as possible, one tube 15 may extend vertically upward for attachment to the evacuating or gascharging tube 7, and. another tube, such as 1, may extend vertically downward and contain metal or other substance to be volatilized into the lamps or bulbs. The lamps or other envelopes 9, to be treated according to my invention, are connected through contraction tubes 11, in any suitable manner, t? tile outstanding tubes 13 of the glass mani o It will be readily understood that, upon heating the metal in tube 1, any desired amount thereof may be introduced into the lamps in a manner similar to that previously described with reference to Fig. 2.

Although I have described my invention with respect to volatile metals, it is to be understood that any other volatile substance suitable for introducing into a lamp bulb or the like may be used within the spirit and scope of my invention which is limited only in accordance with the following claims.

What is claimed is:

1. The method of causing a small-amount of a volatile substance to pass into a vessel connected to an exhaust system and a source of a relatively inert gas, comprising connecting to the exhaust system a tube of said substance, vaporizing a portio'nthereof and sweeping the desired amount of the same into the vessel by a stream of the inert gas.

2. The method of introducing a volatile substance into a vessel, comprising connecting said vessel to an exhaust system, connecting a container of said substance comprising a tubular restricted portion to said exhaust system by said restricted portion, exhausting said vessel and heating said restricted portion until the required amount of said volatile substance is vaporized and passes into said vessel.

3. The method of introducing a small amount of a volatile substance into a vessel, comprising connecting said vessel and a tube of said substance to means for exhausting said vessel, exhausting said vessel and heat in said tube until the desired amount of said substance is vaporized and sweeping a requisite amount of said vaporized substance into said vessel by a stream of inert gas.

4. The method of introducing a volatile metal into a glowlamp -or. the-like, comprising connecting said lamp to means for exhausting the same, connecting a container of said volatile metal with a restricted portion normally closed thereby to said means for exhausting, evacuating the lamp and heating the restricted portion until the desired amount of metal is vaporized and passes into said lamp.

5. The method of introducing a volatile metal into a lamp, comprising connecting said lamp and a'tube of said'volatile metal to a vacuum pump and a source of inert gas, exhausting said lamp, heating said tube until the requisite amount of volatile metal is vaporized and sweeping the desired amount of volatile metal into said lamp by a stream of inert gas.

6. The method of introducing a volatile readily-oxidizable metal into a vessel, comprising connecting said vessel to an exhaust system, preparing a container holdingsome of said metal and comprising a reservoir and a tubular restricted portion extending therefrom, connecting said tubular restricted portion to the same exhaust system near the connection of the vessel thereto, applying heat to said restricted portion to vaporize the requisite amount of volatile metal and causing it to pass intosaid vessel.

7. The method of introducing a readilyoxidizable volatile metal into a vessel, comprisin connecting said vessel to a system for ex austing the same, attaching to said system a reservoir containing a quantity of saidvolatile metal, by means of a tubular restricted portion, exhausting said vessel and heating said volatile metal in said restricted ortion until the desired amount thereof 15 vaporized and passes into said vessel.

8. The method of introducing a small amount of readily-oxidizable volatile metal into a vessel comprising connecting said vessel to a system for exhausting the same, attaching a reservoir 'filled with a quantity of volatile metal to said system for exhausting by means of a restricted tube below the level of the volatile metal, exhausting said vessel and heating said volatile metal in said tube until the requisite amount thereof is vapor-- ized and passes into said exhaust system and sweeping said metal into said evacuated v vessel by means of a stream of inert gas.

In testimony whereof, I have hereunto subscribed my name this 20th day of June, 1922.

CLETUS CLINTON VANVOORHIS. 

